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University of Canterbury people: Karen Pollard Peter Cottrell

Coordinated observational campaigns for non-radially pulsating objects at Mt John Observatory (New Zealand). University of Canterbury people: Karen Pollard Peter Cottrell Duncan Wright (PhD, now post-doc at Royal Observatory of Belgium) Florian Maisonneuve (PhD student)

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University of Canterbury people: Karen Pollard Peter Cottrell

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  1. Coordinated observational campaigns for non-radially pulsating objects at Mt John Observatory (New Zealand) University of Canterbury people: Karen Pollard Peter Cottrell Duncan Wright (PhD, now post-doc at Royal Observatory of Belgium) Florian Maisonneuve (PhD student) Emily Brunsden (BSc (Hons)) Pam Kilmartin (MJUO observer)

  2. Outline • Mt John University Observatory • Location • HERCULES • Asteroseismology Programmes • Spectroscopic observations • Radial velocity measures • Line profile analysis • Specific project: HD49434 • Conclusions

  3. MJUO location • S43°59.2' E170°27.9' and 1031m above sea level • Mt John is located next to Lake Tekapo, South Island, New Zealand • Four telescopes on site: two 0.6m, 1.0m McLellan and 1.8m MOA • Good spectroscopic site (~50%), fair photometric site (~20%)

  4. MJUO location

  5. Mt John University Observatory (MJUO)

  6. Mt John University Observatory (MJUO) • Instrumentation for asteroseismology: • 1.0 m McLellan telescope • fibre-fed High Efficiency and Resolution Canterbury University Large Echelle Spectrograph, HERCULES

  7. MJUO 1.0-m telescope

  8. HERCULES • R ~ 40,000 for 100  fibre or ~ 80,000 for 50  fibre • Gives S/N ~ 100 on a 6th mag object in ~7 min with wavelength coverage from 3800-7500 Å (old CCD 1K x 1K) • New CCD (2K x 2K) has complete wavelength coverage with similar quantum efficiency • New fibre scrambler designed and funded. Installation late 2008. Will improve precision. Design also includes the potential to add an Iodine cell for further precision.

  9. Hercules design and stability • Major elements of HERCULES are fixed to an optical bench inside a cylindrical vacuum tank (4.3 x 1.2 m) where pressure maintained at 1 - 5 torr. The tank is situated in a thermally isolated and insulated room. • RMS stability of 15 m s-1 over time spans of 4 to 5 years is being achieved. • This is ideal for high-resolution, time-series asteroseismological studies of reasonably bright stars (V < 8).

  10. Asteroseismology programmes • In recent years we have initiated and contributed to a number of campaigns to study non-radially pulsating objects: mainly  Sct,  Dor,  Cep stars

  11. Spectroscopic Observations • Binaries

  12. Spectroscopy - line profiles eg  Sct star FG Vir (left) line profile variations (right) grayscale phased difference from mean

  13. Spectroscopy - line profile variations (left) Ca I 612.2 nm line profile (right) Cross correlation profiles

  14. Analysis Tools - Cross correlation • Cross-correlate an object’s spectrum with a template of delta functions (at correct position and depth of each line)  gives a high S/N representative line profile (valid for lines similarly distorted by the pulsation)

  15. Line moments • The periodogram of the first moment (left) shows the periodicities present in the  Scuti star FG Vir, whilst the second moment (right) shows the non-axisymmetric modes (m≠ 0) that are present. • The line moment technique is useful for  Scuti stars where the main line profile variations are line asymmetries.

  16. Specific project: HD 49434 • Ground-based, high-resolution echelle spectra of HD49434 •  Dor star • CoRot target

  17. HD 49434 • MJUO observations 1-18 Feb 2007 • observed by Pollard, Kilmartin • analysed by Emily Brunsden BSc (Hons) project (with additional data at similar time from SOPHIE and FEROS, supplied by Ennio Poretti) • Additional MJUO data: (reduced but not analysed) • 2007 Nov1-6, Nov 21 - Dec 02 with occasional spectra 2007 Dec - 2008 Jan

  18. Data used • HERCULES – New Zealand • FEROS – Chile • SOPHIE- France

  19. Analysis: Radial velocities • Auto cross-correlation of non-telluric orders of HERCULES spectra • Initial results:Δ 6 km s-1 in 16 days  binary? ←6 km s-1 → ←16 Days →

  20. FIGARO and HRSP • Same overall radial velocity variation • HRSP has better internal precision

  21. Collated results • However, no trend seen in FEROS or SOPHIE data • Katrien, using single line analysis, finds no trend in HERCULES radial velocities, although larger scatter ←6 km s-1→ ←49 Days →

  22. Nightly variations ← 1km s-1→ ←3 hours →

  23. Seeing pulsation in spectroscopy 180 min blocks ←90 min → Bruntt et al. (2002) This work

  24. Results • Frequencies of 5, 7 and 11 cycles-per-day  Doradus frequencies  Scuti frequencies

  25. Conclusion • Binary? •  Doradus star? •  Scuti star? • Combination? • More observations of HD 49434 are needed + analysis of all MJUO data

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